1. Field
The present invention relates to a printed circuit board (PCB) and a method of manufacturing the same, and more particularly, to a PCB, which includes bumps formed using a conductive paste including carbon nanotubes and a photosensitive binder, and to a method of manufacturing the same.
2. Description of the Related Art
Conventionally, the formation of solder bumps on a substrate includes a method of printing solder paste on a substrate or a wafer and performing a reflow process (FIGS. 1A to 1E), an electroless plating method, or an electroplating method.
With reference to FIG. 1A, a solder resist 15 is formed on a substrate 11 having pads 13. The solder resist 15 is formed between the pads 13, and functions to prevent the downward flow of solder paste 19 in the subsequent course of forming bumps 23.
As shown in FIG. 1B, a printing mask 17 is located on the solder resist 15. The printing mask 17 functions such that the solder paste is applied to a predetermined height on the pads 13 while preventing the application of the solder paste on the solder resist 15 in the subsequent course of printing the solder paste. As shown in FIG. 1C, the solder paste 19 is printed on the pads 13 using a squeegee blade 21. The solder paste 19 fills recesses defined by the solder resist 15 and the printing mask 17, as shown in FIG. 1C.
As shown in FIG. 1D, the printing mask 17 located on the solder resist 15 is removed, and a reflow process is performed, thereby completing a PCB including bumps 23, as shown in FIG. 1E.
However, the method of forming the bumps of the PCB using printing is problematic in that bumps having a fine pitch of 120 μm or less are difficult to realize. Thus, the method of forming the bumps using printing cannot be applied when it is intended to form fine bumps. Even if such bumps are formed, the volume thereof becomes very small.
Presently, the size of a PCB, which enables the formation of bumps through printing, approximates a quarter size or a half size. Hence, it is impossible to perform a panel-size bumping process.